Patent EA-004452-B1 (EA)
Title: Arrangement at a piston engine and method of controlling the pistons
Inventor: MOE MAGNE
IPC: F04B1/14
Filed: 2001-09-13
Abstract: 1. An arrangement at a piston engine in the form of a piston pump/engine (motor) of the type in which two or more co-operating piston cylinders (14, 14a, 14b, 14c,), the reciprocating pistons (16, 16a) of which have rods (18, 18a, 18b, 18c) following a rotatable cam (12, 50) directly or indirectly, characterised in that the cam (12, 50) has a set of sectors of continues and complementary varying slopes, such that if the cam is rotated at a constant angular speed, the sum of linear speed of all pistons following the sectors of positive slopes is constant and equal to the sum of linear speed of all pistons following the sectors of negative slopes. 2. An arrangement according to claim 1, characterised in that the said cam (12) is symmetrical and the number of pistons is a multiple of odd numbers equal to or larger than three. 3. An arrangement according to claim 1, characterised in that the said cam (12) is asymmetrical and the number of pistons is a multiple of even numbers equal or larger than four. 4. An arrangement according to claim 1, 2, or 3, characterised in that the free outer end of each piston rod (18, 18a, 18b, 18c) is constituted by that portion of the abutment surface of the peripheral surface of a rotatable roller (20, 20a, 20b, 20c) which at any time is furthest out in the axial direction, which peripheral surface shall at any time abut the surface (52) of the cam (12; 50). 5. An arrangement according to claim 1 or 4, characterised in that the cam is constituted by an encircling cam ring (50) arranged on a rotatable drum (44), cylindrical body or similar device, means or structure. 6. An arrangement according to claim 4, characterised in that said rotatable rollers (20, 20a, 20b, 20c) are designed at any time to be kept in elastic/resilient abutment against said cam surface (12; 52). 7. An arrangement according to claim 6, characterised in that the piston rod ends for support of their respective abutment rollers (20, 20a, 20b, 20c) are formed with a bifurcated head (18b') designed to accept the abutment roller rotatably between the U-branches with the aid of a transverse bolt (54). 8. An arrangement according to claim 4, 6 or 7, characterised in that means (e.g. 56) designed to ensure the establishment and maintenance of a sufficiently high pressure on the suction side to compensate for the frictional, gravitational and inertial forces that seek to lift the abutment roller (20, 20a, 20b, 20c) off the guide surface (52) of the cam (50). 9. An arrangement according to claim 8, characterised in that said means are constituted by spring biasing means, e.g. pneumatic devices (16A, 14B), mechanical means such as springs etc. 10. An arrangement according to claim 7, characterised in that the bifurcated head (18b') at the end of each piston rod (18, 18a, 18b, 18c) supports an axially projecting holder (60) designed to ensure that the abutment roller (20b) is kept in spring loaded contact with the cam surface (52) of the cam. 11. An arrangement according to claim 8, characterised in that said holder (60) has a U-shaped form, a first U-branch being directed axially away from the bifurcated outer, free piston rod head (18b'), while the other U-branch, which is connected to the first U-branch via the U-web that forms a transverse connecting piece, is directed axially towards the-piston rod head (18b') and supports a contact wheel (56), the peripheral surface of which abuts the rear ring surface (52a) of the cam ring (50) in a spring loaded manner, opposite the cam surface (52) of the cam, for the purpose of keeping the abutment roller (20b) in constant, resilient abutment against the cam surface (52). 12. An arrangement according to claims 7, 8 and 11, characterised in that said bifurcated head (18a'-18c') is designed for support of both the abutment roller (20a-20c) and the contact wheel/counter roller (56) on the opposite side of the cam ring (50) relative to the actual cam surface (52). 13. A method of controlling controllable-reciprocating pistons (16, 16a) in piston cylinders (14, 14a, 14b, 14c) that, numbering two or more, form part of a piston pump or piston engine, in which rotatable means are provided for the mutual control of the piston strokes, which means influence the pistons via their projecting piston rods (18, 18a, 18b, 18c), characterised in that each piston (16, 16a) is driven at a constant speed through part of its power stroke and that at least one piston is driven in a such a manner that its speed profile/curve is asymmetrical, i.e. constant but with different speeds for the power stroke and the return stroke. 14. A method according to claim 13, characterised in that the pistons (16, 16a) are driven in such a manner that the piston speed is changed gradually to or from zero at the end of a power stroke, and in such a manner that when a working piston decelerates to zero speed, the (or one of the) co-operating piston, which at the same time commences a power stroke, is accelerated from zero speed. 15. A method according to claim 14, characterised in that each piston (16, 16a) decelerates and accelerates linearly at the end and commencement, respectively, of a power stroke, so that the sum of the speed of the pistons during the change-over phase is constant and equal to the speed at which the piston normally works during the power stroke. 16. A method according to one or more of the preceding claims 13-15, characterised in that a constant, maximum piston speed is established and maintained through part of the power stroke. 17. A method according to one or more of the preceding claims 13-16, where the piston engine is constituted by a pump and work is performed with two diametrically opposed piston cylinders (14, 14a) and an intermediate cam (12), characterised in that each power stroke is brought to cover a little more (e.g. 30 degrees) than 180 degrees rotation of the drive shaft (10), so that both pistons (16, 16a) simultaneously execute part of a power stroke during the overlapping part of a rotation, where one of the pistons is decelerated steadily towards zero and ends this power stroke, while the other piston commences its power stroke and is accelerated steadily towards a full power stroke, and where the return stroke is executed at a higher speed than the actual power stroke.